ph COOLING TOWER CONTROLLER

Transcription

1 LAKEWOOD INSTRUMENTS MODEL 350 ph COOLING TOWER CONTROLLER INSTRUCTION MANUAL SERIAL #: Lakewood Instruments 7838 North Faulkner Road, Milwaukee, WI USA Phone (800) Fax (414)

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3 Lakewood Instruments Congratulations on your purchase of a Lakewood Instruments controller. We would like to take this opportunity to welcome you to the Lakewood Instruments product family. With proper care and maintenance, your controller should give you many years of trouble-free service. Please take the time to read and understand the operation manual, paying special attention to the sections on INSTALLATION and MAINTENANCE. If, in the future, any parts or repairs are required, we strongly recommend that only original replacement parts be used. Our Customer Service Department would be happy to assist you with your parts or service requests. We thank you for your selection and purchase of a Lakewood Instruments product. 3

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5 MODEL 350 CAUTIONS PLEASE READ THIS IF THIS CONTROLLER IS USED TO FEED ACID ONLY FOR ph CONTROL: 1. Turn the caustic feed set point knob full counter-clockwise. 2. Make sure that the caustic AUTO/MANUAL switch is in AUTO. FAILURE TO OBSERVE This will cause the acid pump to time out even if no acid is being pumped. This is because the caustic pump set point and control also actuates the alarm timer. IF THIS CONTROLLER IS USED TO FEED BOTH ACID AND CAUSTIC: 1. Make sue that the low caustic set point is set at a lower ph than the acid feed set point. 2. Make sure that both AUTO/MANUAL switched are in AUTO. 3. DO NOT AT ANY TIME cause both acid and caustic to be pumped at the same time. FAILURE TO OBSERVE this may cause both acid and caustic to be fed at the same time. The resulting reaction could be violent and extremely dangerous. DO NOT turn the sensor lock ring with pressure in the sensor flow cell. Release the pressure first. The sensor may fly out of the flow cell if the pipe is under pressure and injure someone. 5

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7 MODEL 350 Table of Contents GENERAL DESCRIPTION 9 Introduction 9 INSTALLATION 11 Checking 11 Wiring 11 FEATURES 13 Setpoints 13 Alarm Timer 13 Flowswitch 14 ph Sensor 14 Chart Recorder 14 ADD ON OPTIONS ma output 15 39F Frequency output High/Low Alarm output 15 CALIBRATION 17 Method 1 17 Method 2 17 Method 3 17 START UP 19 Start Up 19 MAINTENANCE AND TECHNICAL SERVICE 21 Technical Service 21 Service Guide 21 Parts List 22 Troubleshooting 22 DRAWINGS 23 7

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9 INTRODUCTION The Model 350 allows you to control acid and/or caustic feed in order to maintain desired ph levels in your cooling tower. This model features an alarm timer which prevents excessive chemical feed and a flowswitch which prevents chemical feed if there is no sample flow. For cooling tower applications only. Includes plumbing. SPECIFICATIONS Inputs Power Sensor Flow switch 120 VAC 120/240VAC w/-wp ph Combination glass electrode in PVC housing. Dry contact Outputs Relays VAC 4-20 ma isolated, internal power w/-35 Plumbing Pressure F (38 C) Max. Temperature 140 F (60 C) Min. Flow 1 gpm Controller ph Range Accuracy Resolution Deadband Setpoints Alarm Timer Ambient Temperature Electrical Rating Enclosure Rating 5-10 ph ±0.05 ph 0.01 ph Adjustable HIGH and LOW 5-90 minutes. Locks out both HIGH and LOW setpoints F (0-70 C) UL Listed ABS Plastic NEMA 4X Optional 9

10 ORDERING INFORMATION 350 ph controller for acid and caustic feed that has dual setpoints, 5-10 ph scale, a feed limit timer with pushbutton reset, flowswitch, sensor, power cord, outlets and a digital display. UL Listed. CONTROLLER OPTIONS (optional) -CRPH Custom setpoint dial; 0-14 ph REMOTE SENSOR OPTIONS (optional) -RPFS Unlimited distance. Preamp, sensor, flowswitch and sensor tee. Cable must be provided by customer ENCLOSURE OPTIONS (optional) -WP NEMA 4X watertight enclosure with 120/240VAC 50/60 Hz power switch. No outlets or power cord. PLUG-IN OUTPUT OPTIONS (optional, select one only) -35 Isolated 4-20 ma output for remote data acquisition. -39F Frequency output contact for electronically pulsed chemical pump. -39P Percent on-time modulating contact for solenoid chemical feed systems. -42 HIGH/LOW alarm contacts with adjustable setpoints. -44 Isolated 4-20 ma output plus HIGH/LOW alarms. 10

11 INSTALLATION Checking Inspect the shipping carton for obvious external damage. Note on the carrier's bill-of-lading the extent of the damage, if any, and notify the carrier. Save the shipping carton until your Model 350 Controller is started up. If there was shipping damage, call the Lakewood Instruments Customer Service Department at (800) for authorization to return the controller to the factory in the original carton. Check the power wiring. Make sure that the controller is powered from 120 VAC unless it is specifically set up for 220 VAC. Check the recorder or other low power wiring. MAKE SURE THAT NO POWER WIRING IS CONNECTED TO ANY LOW POWER CIRCUITS. MAKE SURE THAT THE TWO RED LOCK RINGS ARE FULL CLOCKWISE AND LATCHED BEFORE TURNING ON THE SAMPLE LINE FLOW. THE FLOW SIGHT FITTING AND THE SENSOR WILL BLOW OUT IF NOT SECURELY LATCHED. Check the plumbing for leaks. Check also for the proper flow direction. It takes 1 GPM to raise the float ball valve above the lip of the clear flow sight tube. Check the chemical pump fittings. Make sure that they are safe. Not overtight but tight enough. Wiring The standard 350 is prewired and preplumbed for easy installation. If the -WP option is included in your 350 wiring will be required. -RP or -RPFS options will required special wiring for the ph sensor input because it uses a preamp. Refer to the diagrams in back of this manual for installation. 11

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13 FEATURES Setpoints The Model-350 ph controller is intended for acid and/or caustic feed to maintain the water ph in air conditioning cooling tower systems. It is necessary for sample piping to be run from a circulating water pump to the controller. A flow switch on the controller prevents chemical feed if there is no sample flow. Another safety feature includes an alarm timer that prevents excessive chemical feed. Acid is normally used in cooling water ph control. As the cooling water evaporates the make up water alkalinity is concentrated and the ph rises. As the ph rises over the acid feed set point, a relay closes the circuit to the acid pump and turns it on. Acid is fed into the water. As the ph drops below the set point due to the acid, the relay turns off the acid pump. Caustic is sometimes used to control the ph in cooling towers with corrosive make up water. It is needed if the tendency of the water is toward a lower ph. Low ph below the caustic feed set point will close the caustic feed relay and turn on the caustic chemical pump. As the ph rises about the set point, the relay will open and turn off the caustic pump. In cooling water applications, the caustic feed set point can serve as a LOW alarm set point. Wire the alarm horn, light, buzzer or relay to the caustic feed pump terminal. See the wiring diagram. Alarm Timer The alarm timer limits the amount of continuous acid or caustic feed. For example, if the alarm timer is set on 30 minutes, only 30 minutes of acid can be fed continuously without the set point turning the acid pump off. The alarm timer automatically resets when the acid pump turns off or when the RESET button is pushed. The same applies to caustic feed. If acid or caustic is not being used be sure to adjust the setpoint in a position where it will not turn on. 0 ph for caustic and 14 ph for acid. To determine proper settings, consult your water treatment professional. 13

14 Flowswitch The flow switch locks out all chemical feed and the alarm timer if there is no sample line flow. Only 1 GPM is needed to raise the flow switch. Special flow switch assemblies are available for extremely low flows and are available on special order. A flow sight assembly shows the black ball at the top of the flow switch float. When the ball is above the rim of the finger grip ring, the flow switch is on. The flow sight may be cleaned by turning off the sample flow and turning the red ring lock counter-clockwise. Then twist out the flow sight assembly. It is O ring sealed. Clean the flow sight insert with a cotton swab. ph Sensor The ph sensor is a non-temperature compensated combination electrode. To remove the sensor, shut off the sample flow and turn the red lock ring counter-clockwise to the stop. Twist out the O ring sealed sensor. Clean the sensor in dilute hydrochloric (10% HCI or muratic) acid. Wash in tap water. TAKE PROPER PRECAUTIONS WHEN HANDLING ACID. WEAR EYE PROTECTION! DO NOT WIPE THE GLASS BALL WITH ANYTHING! IT IS VERY THIN SENSITIVE GLASS AND YOU MAY DAMAGE IT! Replace the ph sensor in the flow cell assembly. Make sure the O ring is clean. Turn the red lock ring clockwise until it snaps into place. NOTE: NEVER ALLOW THE ph SENSOR BECOME DRY. DOING SO WILL DAMAGE THE SENSOR Chart Recorder Output The Model 21 inkless strip chart recorder requires two connections to the Model 350 back board. Refer to Figure 1.3. The chart recorder motor requires 120 VAC, 60 Hz unless specified otherwise. The chart recorder manual is attached to this manual. Refer to the recorder manual for proper loading of the chart paper. 14

15 ADD ON OPTIONS Only one add-on option below can be added to the 350 controller 35 Isolated 4-20 ma output The 35 plug in circuit board provides an isolated 4 to 20 ma output to a computer or control device. The load resistance must not exceed 800 ohms. The output is factory preset for 5 ph = 4 ma and the 10 ph = 20 ma. ZERO and SPAN adjustments permit scaling the output to another desired conductivity range. Refer to drawing for component locations. Equipment required: ph simulator such as the Model APS2 and a current meter for the loop current. To set the range, make the Model 350 read the desired 4 ma ph valve. Then adjust the output board ZERO for 4 ma loop current. Next, set the Model 350 on the desired 20 ma ph valve. Then adjust the SPAN to give the 20 ma loop current. 39F Chemical pump frequency proportional output This option provides a 100 ms relay closure. The frequency of operation is from 0 to 100 pulses per second maximum. The output is intended to operate a solenoid type chemical pump with external pulsing connection. Equipment Required: a ph simulator such as the Model APS2. ZERO and SPAN adjustments are on the board. Refer to drawing A for component locations. To set the range, make the Model 350 read the desired 4 ma ph valve. Then adjust the output board ZERO until the chemical pump just stops pulsing. Next, set the Model 350 on the desired ph for the maximum pulse rate output. Adjust the SPAN to give the maximum pulse rate at that ph. 42 HIGH/LOW alarms for remote alarm status or computer alarm log To set alarms, simulate the LOW ph trip point with a Model APS2 simulator or zero shift of the Model 350 STANDARDIZE (STD). Make the Model 350 read the LOW trip point. Adjust the LOW alarm on the board until the relay just pulls in. To set the HIGH alarm, make the Model 350 read the desired HIGH ph trip point. Adjust the HIGH adjustment on the plug in board until the relay just pulls in ma output and HIGH/LOW alarms The 44 card is a option that includes the features of the 35 and 42 card. 15

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17 CALIBRATION Method 1 Method 2 Measure a sample of cooling tower water with handheld meter. Adjust the STANDARDIZE (STD.) to make sure the controller display agrees with the handheld. Verify calibration with a millivolt/ph simulator such as the Lakewood APS2. At 7pH adjust the STANDARDIZE (STD.) to make sure the controller display agrees with the millivolt/ph simulator. Method 3 Obtain 7 ph buffer solution. Obtain a short piece of hook up wire. Attach one end of the hook up wire to Test point 1 on the rear of the front panel. Place the other end in the 7 ph buffer solution. Place the sensor tip in the buffer solution. Adjust the STANDARDIZE (STD) so that the display reads 7.00 ph. Place the sensor back in service. 17

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19 Calibrate the ph on the 350 controller before any chemical feed control is top begin STARTUP Set the acid feed set point (HIGH set point) at the desired level. This is the ph at which the acid pump turns on when the ph is above the set point. This is usually from 6.8 to 8.0 ph. Consult your water treatment engineer for the correct valve for the type of treatment used. With water flow through the controller flow cell, press the ACID AUTO/MANUAL switch to MANUAL. The acid pump should turn on. Press the switch again to return to AUTO. Set the caustic feed set point (LOW set point) for your low alarm ph is caustic is not used. Usually this will be at 6.0 ph unless advised otherwise. If you are feeding caustic adjust the caustic feed set point as required. This is the value that the caustic pump will turn on if the ph is below the set point as required. This is the value that the caustic pump will turn on if the ph is below the set point. It will usually be at or above 7.0 ph. With water through the controller flow cell, press the CAUSTIC AUTO/MANUAL switch to MANUAL. The caustic pump should turn on. Press the switch again to AUTO. Always consult your water treatment professional for proper settings for you system. 19

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21 Maintenance and Technical Service Technical Service Technical Support for Lakewood Instruments can be reached by calling (800) or faxing (414) , Monday through Friday, 7:30 a.m. - 5:00 p.m. CST. Mail and returns should be sent to: Lakewood Instruments 7838 North Faulkner Road Milwaukee, WI USA When any merchandise is returned to the factory, please call and obtain a Return Goods Authorization (RGA) number and have the following information available: Customer s name, address, phone and fax numbers. A purchase order number (no exceptions) for cases where parts are required that are not under warranty. A contact person s name and phone number to call if the equipment is beyond repair or to discuss any other warranty matter. Equipment model and serial numbers. Reason for return (i.e., repair, warranty, incorrect part, etc.). We will then fax to your attention an RGA form that must accompany the returned item. NOTE: THE RGA NUMBER MUST BE CLEARLY WRITTEN ON THE OUTSIDE OF THE PACKAGE(S) BEING RETURNED. Service Guide When calling Lakewood Instruments, please have the controller s complete model number and serial number available so that the technician can better assist you. When any parts are returned to the factory, please indicate: Customer s name and address Individual at customer location to send the repaired controller or new part to The person (and phone number) to call if the equipment is beyond repair or for any warranty matter 21

22 Parts List PART NUMBER DESCRIPTION ph combination replacement electrode Plumbing assembly including flow switch Replacement flow switch float Replacement flow switch-reed switch assembly Flow Sight Troubleshooting PROBLEM CORRECTIVE ACTION ph doesn t respond to Replace the ph sensor changes or won t calibrate. Check the controller with an APS2 simulator. Wild ph swings with poor Check solution gnd wire. Suspect poor acid/caustic control. mixing in water. Acid/caustic pump stroke set too high. ph sensor too old. Needs replacement. Acid pump alarm timer Out of acid/caustic. actuates. Acid/caustic pump lost prime. Acid/caustic pump stroke set too low for the size of the cooling system. Alarm Timer set too low. Make up water changed. No output to chemical Is the flow light on. pump. Defective flow switch. Defective acid pump. Plug into hot outlet. Nothing happens. Is there power to the controller? Is the fuse on the rear circuit board blown? Is there power to the terminals on the rear circuit board? 22

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37 Copyright 1997 Lakewood Instruments, LLC. Printed in USA, P/N Rev. 1

38 For more information call toll free in the USA (800) Manufactured in the USA Lakewood Instruments 7838 North Faulkner Road, Milwaukee, WI USA Phone (414) Fax (414) Copyright 1997 Lakewood Instruments, LLC. Printed in USA, P/N Rev. 1